School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK.

Erratum in

Phys Rev Lett. 2010 Dec 31;105(26):269906.

Abstract

We present composite plasmonic nanostructures designed to achieve cascaded enhancement of electromagnetic fields at optical frequencies. Our structures were made with the help of electron-beam lithography and comprise a set of metallic nanodisks placed one above another. The optical properties of reproducible arrays of these structures were studied by using scanning confocal Raman spectroscopy. We show that our composite nanostructures robustly demonstrate dramatic enhancement of the Raman signals when compared to those measured from constituent elements.